1. Field
Exemplary embodiments of the present invention relate to a hub bearing; and, particularly, to a magnetic encoder type hub bearing unit capable of reducing an air gap and minimizing contamination on a wheel speed sensor (hereinafter, referred to as “WSS”) head due to external foreign matters by preventing exposure of the WSS to the outside.
2. Description of Related Art
In general, a vehicle wheel is provided with a hub bearing is located between a disc part to which a brake is mounted and a bracket forming a suspension. The hub bearing is equipped with a magnetic encoder linked with a WSS.
Thus, a structure in which the hub bearing, the WSS, and the magnetic encoder are linked to each other is referred to as a magnetic encoder type hub bearing.
In this structure, the magnetic encoder is located within a steel cap for covering the hub bearing so as to prevent exposure of the magnetic encoder to the outside, and the WSS is installed at the magnetic encoder in the outside of the steel cap so that an air gap is formed between the WSS and the magnetic encoder and the WSS is exposed to the outside.
Typically, sensitivity of the WSS to the magnetic encoder may be improved as the air gap affecting performance of the WSS becomes smaller.
However, since the WSS is mounted outside the steel cap, the air gap may be increased due to an assembly tolerance between the WSS and the steel cap.
In particular, since the air gap is set by a distance between the encoder and the steel cap, a thickness of the steel cap, and a distance between the steel cap and the WSS, there is a limit in reducing the air gap.
In addition, since the WSS is exposed to an external environment, a WSS head for sensing the magnetic encoder may be contaminated due to external foreign matters. Particularly, a possibility of malfunction of the WSS may be significantly increased due to introduction of magnetic foreign matters through the air gap.